1. Field of the Invention
The subject invention pertains to the production of fibrous products using a binder. More particularly, the present invention relates to an improved method of applying liquid binder to the fibrous products.
2. Description of the Related Art
The rotary process for producing glass fibers is well established. A stream of molten glass is delivered to an open spinning disc containing multiple orifices that causes fibers to extrude from the disc sidewall. The extruded fibers are directed downwardly toward a moving chain by pressurized air from nozzles in an annular ring positioned above the disc or by the jet blast of a gaseous combustion system. As the fibers fall from the spinning disc a rotating column of glass fiber is formed, which is sprayed with binder that is later cured, after sizing, in an oven. Typically the binder is sprayed onto the fibers from a number of inwardly directed nozzles mounted circumferentially around the fiber column just below the disc.
The tendency of the small orifices in the spray nozzles to become clogged or plugged however, causes uneven binder distribution in the finished product. In addition, the spray nozzles and associated headers and piping collect and trap fibers laden with binder which can accumulate into clumps that eventually become dislodged and deposited in the fiber blanket causing uneven density and product color. Changes in binder viscosity or flow rate necessitate further changes in spray orifice size or increasing/reducing the number of spray nozzles to maintain a constant binder droplet size. Furthermore, it is difficult for an inwardly directed binder spray to uniformly penetrate the dense fiber column, thus leaving some fibers without binder. In attempting to provide continuous coverage of the fiber column the spray nozzles are often configured in an overlapping spray pattern that often results in binder collecting on the collection chamber walls. Non-uniform coating of the glass fibers with binder results in variable physical properties from one section of the product to another. Therefore, it is highly desirable to have an improved method of binder application.
U.S. Pat. No. 5,123,949 describes a process for introducing additive particles to extruded fibers during the production of the fibers. The additive particles are delivered from the inside of the column of fibers. Liquid binder can also be sprayed concurrently with the additive particles from the inside of the column. As discussed in the patent, some of the binder is intercepted by the additive particles. Additional liquid binder can be sprayed onto the fibers using nozzles external to the fiber column, if desired.
Still, better binder efficiency is desired and important to rendering the overall process more efficient. A process for applying binder more effectively and efficiently would greatly enhance the commercial viability of a fiberglass product such as insulation.
Accordingly, it is an object of the present invention to provide one with a more efficient process of applying binder to glass fibers.
It is another object of the present invention to provide a more efficient and effective process for applying binder to glass fibers prepared by a rotary process.
Another object of the present invention is to provide a novel process with improved binder efficiency which avoids the problems of plugging or clogging, and which is independent of the binder solution viscosity.
These and other objects of the present invention will become apparent to the skilled artisan upon a reading of the following specification and the Figures of the drawing, and the claims appended hereto.